1. Field of the Disclosure
The present disclosure relates to a liquid crystal display (LCD) device, and more particularly, to a horizontal electric field-type LCD device including a polymer network formed using a reactive material and a method of fabricating the same.
2. Discussion of the Related Art
In general, a liquid crystal display (LCD) device may be driven based on optical anisotropy and polarization of liquid crystals (LCs). Since LC molecules are thin and long, the LC molecules may be arranged in a specific direction, and a direction in which the LC molecules are arranged may be controlled by artificially applying an electric field to LCs.
That is, when the arrangement of the LC molecules is changed using an electric field, light may be refracted due to the optical anisotropy of the LCs in the direction in which the LC molecules are arranged, so that images can be displayed.
In recent years, an active-matrix LCD (AM-LCD) device in which TFTs and pixel electrodes are arranged in matrix shapes has attracted much attention because the device has a high resolution and is highly capable of embodying moving images.
A typical twisted-nematic (TN)-mode LCD may include an array substrate having pixel electrodes, a color filter substrate having common electrodes, and an LC layer interposed between the array substrate and the color filter substrate. In the TN-mode LCD device, the LC layer may be driven due to a vertical electric field generated by the common electrodes and the pixel electrodes. Also, the TN-mode LCD device may have a high transmittance and a high aperture ratio.
However, the LCD device in which the LC layer is driven due to the vertical electric field may have poor viewing angle characteristics.
To overcome the disadvantages of the TN-mode LCD device, a horizontal electric field-type LCD device having good viewing angle characteristics, such as a fringe-field switching (FFS)-mode LCD device or an in-plane switching (IPS)-mode LCD device, has been proposed. An FFS-mode LCD device will now be described with reference to FIG. 1 as an example of the horizontal electric field-type LCD device.
FIG. 1 is a cross-sectional view of a conventional FFS-mode LCD device 10.
Referring to FIG. 1, the FFS-mode LCD device 10 may include first and second substrates 20 and 30 disposed opposite and apart from each other and an LC layer 70 interposed between the first and second substrates 20 and 30.
A first electrode 40 having a plate shape may be formed on an inner surface of the first substrate 20, and an insulating layer 42 may be formed on the first electrode 40.
A plurality of second electrodes 50 having bar shapes may be formed on the insulating layer 42 and spaced apart from one another. A first alignment layer 60 may be formed on the plurality of second electrodes 50.
In addition, a second alignment layer 62 may be formed on an inner surface of the second substrate 20.
The LC layer 70 may be formed between the first and second alignment layers 60 and 62. Major axes of LC molecules 72 of the LC layer 70 may be horizontally arranged parallel to the first and second substrates 20 and 30.
When different voltages are applied to the first and second electrodes 40 and 50, an electric field may be generated between the first and second electrodes 40 and 50. The LC molecules 72 of the LC layer 70 may rotate on a horizontal plane surface due to the electric field and be rearranged to display an image.
In the FFS-mode LCD device 10, since the LC molecules 72 of the LC layer 70 are always rearranged on the plane surface parallel to the first and second substrates 20 and 30, viewing angles may be improved in vertical and lateral directions on the basis of a front surface of the LCD device 10.
However, unlike a conventional vertical electric field-type LCD device, in a conventional horizontal electric field-type LCD device, a strong electric field may be generated only in a region adjacent to an electrode disposed on an inner surface of a first substrate, and a weak electric field may be generated in a region adjacent to a second substrate. Thus, LC molecules present in the region adjacent to the second substrate may be driven more slowly than LC molecules present in the region adjacent to the first substrate.
Furthermore, since the rotational viscosity of LC molecules of an LC layer increases with a drop in ambient temperature, as an ambient temperature decreases, an LC response time of a conventional horizontal electric field-type LCD device may increase, and a response speed thereof may be reduced.